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rigidity modulus of polyurethane rubber Question
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Posted by: antony

05/25/2004, 05:50:09

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we are using a portion (35mm)of a round belt as a torional spring in one of our applications. We want to calculate the torsional rigidity modulus of the material. We have designed a test rig to apply a torsional load & to measure the angle of twist. From this, we have arrived at the answer.

Since the material is non-linear, rigidity modulus is not a constant value.

The problem we are facing is that consistent angle of twist values are not obtained for the same torsional load and hence the torional rigidity modulus values are also inconsistent.

What may be reason for this?

With thanks,
C.M.Antony Thomas

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Rigidity modulus of polyurethane rubber
Re: rigidity modulus of polyurethane rubber -- antony Post Reply Top of thread Forum
Posted by: RandyKimball
05/25/2004, 20:54:15

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Are you using test coupons or a round chunk? (I'm confused)
Are you using consistant duro's as a control test group?
Are you testing different blends and duro's in group lots of the same to bracket the tests?

Generally a test coupon is used to perform shear, tear, "torque", or whatever lab R&D tests with equipment that can be trusted to induce almost no variance in the test groupings. Then the data is multiplied to fit the actual engineering project or published criteria. I'm fairly sure poly will come in many different blends and property effects according to who produced it. My experience is that it is best suited for compression actions rather than torques, but I know little about this subject. I use it for its compression spring quality.

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Modified by RandyKimball at Tue, May 25, 2004, 20:55:42

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